The "question" ... that's the part you cut off so we can't see it ... is important.
What's the question for Part-A ? Is there also a Part-B ? What's the question in THAT part ?
There are two different questions that could be asked about this train, and they have different answers.
Question #1: What's the total distance the train travels ? That's 10.3 km.
Question #2: What's the train's displacement after it's all over ? That's 2.3 km.
It's pretty tough to find the correct answer when we don't even know the question.
